The present invention relates to electronic circuits and more particularly, to negative resistance networks.
Circuit elements characterized by a negative resistance are well known in the art. Examples of such devices which may be configured to exhibit a negative resistance characteristic are transistors, semi-conductor pn junctions and Gunn devices. These devices exhibit negative resistance characteristics only over specific frequency bands and are limited in the maximum power handling capability. There are many applications where amplification is desired to provide power levels at frequencies for which there are no presently known negative resistance devices suitable for use with well-known negative resistance amplifier configurations. In many such cases, the desired power level could be attained at lower frequencies using presently known negative resistance devices, but not at the desired frequencies. Where amplification is required at power levels and frequencies for which negative resistance devices do not exist, the prior art teaches the use of travelling wave tubes in spite of the accompanying disadvantages compared with solid state circuits.
The present invention may also be used in relatively low power high frequency applications. In some such configurations, the associated noise figure is relatively low compared with that attained using presently-known circuits.
An alternative approach known in the prior art is to use a frequency convertor to image low frequency circuit components (such as a negative resistance diode) at a high frequency, see U.S. Pat. No. 3,588,727. However, this approach is subject to a substantial disadvantage since such a convertor requires relatively complex circuitry including an active circuit means for generating a pump signal for transforming the convertor input signal to an output signal at the desired frequency.
It is an object of this invention to provide an improved network characterized by a negative resistance at frequencies and power levels which are higher than those of available negative resistance devices.
Another object of this invention is to provide an improved negative resistance amplifier for operation at relatively high frequencies.
It is still another object of this invention to provide an improved negative resistance oscillator for operation at relatively high frequencies.
A further object of this invention is to provide an improved negative resistance oscillator which may be injection locked at relatively high frequencies.
Yet another object is to provide circuit configurations characterized by a relatively low noise figure.